Esters of 1, 4-butanediol and 1, 2, 4-butanetriol as rust inhibitors



ESTERS OF 1,4-BUTANEDIOL AND 1,2,4-BUTANE- TRIOL AS RUST ITORS .loseph ICopas, Easton, Pa., assignor to General Aniline & Film Corporation, NewYork, N.Y., a corporation of Delaware No Drawing. Filed June 13, 1957,Ser. No. 665,611 (Cl. 252-57) the surface and prevent rusting for longperiods of time.

When however there are moving parts in the article, especially when theyare nicely fitted and require lubricant protection, many ditficultiesappear.

ered with heavy coats of paint since such a covering interferes with themovement of the respective parts, and

in addition rapidly wears away, causes undesirable dimen-,

sion changes, and is very difficult to prepare without pinholes thereinwhich, when present, largely destroy the rust protection. Accordingly acoating of some sort which is both a lubricant and a rust preventer ishighly desirable. Many substances have been tried of which perhaps thebest previous one is a mixture of sulfonated corn oil in a petroleumproduct such as lubricating oil or Vaseline or paraffin or the like.Many other rust preventers have also been proposed including varioussalts and esters of many organic acids; various of the airlines; variousesters and many other chemical compounds, which may in addition requirecosolvents, synergists,

They cannot be cov- .phorus trichloride, phosphorus pentachloride,

chloride, and the like.

auxiliaries, and the like. None of the substances previously known are,however, fully satisfactory since they tend to yield gummy deposits orprovide insufficient protection or contain heavy metal substances whichcause precipitation and which when heated yield troublesome q ashresidues and the like. Some of the others are expensive, or are in shortsupply, or decompose too easily through hydrolysis or through thermaleffects or undesirably alter the system.

According to the present invention it is now found that the esters ofbutanediol and triol, especially if the esterifying acid is ofrelatively high molecular weight; that is, has more than 8 or 10 carbonatoms per molecule and particularly if there is a unit of unsaturationin the esterifying organic acid, yield outstandingly good rustinhibitors, which are, in addition, good lubricants, are compatible'withother lubricants in general; yield no ash upon combustion and aresufficiently adhesive and film forming to stay in place for substantialperiods of time without draining, rubbing or wearing ofi.

Accordingly these esters are highly desirable as lubricant additivesespecially in internal combustion engine oils since they do not gum whenheated, do show an adequate heat resistance, show a substantiallubricating effect, do not substantially alter the viscosity index, donot decompose unduly in the presence of water, and in addition do notdeposit ash or other incrustations which may lead to the fouling ofspark plugs, piston rings, valves, and the like, nor do they build upresidues in the engine cylinders,

Other objects and details of the invention will be apparent from thefollowing description.

The primary reactant to form the compositions of matter of the presentinvention is found in 1,4-butanediol or 1,2,4butanetriol. Thesecompounds are prepared, as is Well known in the art, by the condensationof acetylene and formaldehyde to yield 2-butyne-1,4-diol when passedover a copper acetylide catalyst at moderately elevated temperature andpressure. The resulting 2-butyne-1,4- diol which results from thisprimary reaction may then be hydrogenated to 1,4-butanediol by anyconvenient reducing or hydrogenating procedure, hydrogen under pressurein" the presence of a nickel catalyst being the preferred procedure.Alternatively the hydrogenation may be accomplished by hydrolysis withwater in the presence of mercury salt catalyst to yield 1,4-dihydroxy-2-butanone and subsequent hydrogenation to yield the 1 ,2,4-butanetriol.

These methods of producing the butanediol and butanetriol are well knownand Well reported in the literature both in patents, textbooks, PBReport 60574, FIAT 1003, and other places.

These two compounds are readily esterified by any desired acid,esterification by organic acids having more than about 12 carbon atomsper molecule then yields the new rust inhibitor of the presentinvention. The preferred method of esterification is through the use ofacid chlorides of the desired esterifying acid. The preferred;

organic acid is found in the oleyl group.

- In practicing the invention the butanediol or triol may;

first be prepared by the above processes well known in the art. Theseprocesses are outlined broadly above, and the details are well known tothose skilled in the art and need not be repeated here.

The butanediol and triol having been procured are then esterified. Thismay be done by forming the acid chloride of the desired organic acid byreaction with phosthionyl The acid chloride and the alcohol are thenheated to- "the partial esters, to add the acid chloride to the alcohol.

The reaction proceeds with the evolution of hydrogen chloride. It isusual in the laboratory to add an acid acceptor such as pyridine, to thereaction mixture. This absorbs the hydrogen chloride and allows thereaction to proceed. When the reaction is completed, the ester may beremoved from the slurry by taking advantage of the diverse solubilities,the esters having but slight solubility in water. Various othertechniques may also be employed. It is not necessary to distill theproduct.

The resulting mono or di esters of the diol, and mono, di and tri estersof the triol then form the rust inhibitor to be added to the variouslubricants or diluents in small amounts. Depending upon the size of themolecule of the esterifying acid, these esters are mobile liquids,relatively viscous liquids, highly viscous liquids, waxes or solids. Itdoes however appear that the molecular weight is of importance in therust inhibiting action, the higher molecular weight acids at least aboveC being best, the lower nary temperatures which are readily soluble inlubricab;

Patented Mar. 21, 1961 These reactions are well known ing oils and otherhydrocarbons and when so dissolved I bon atoms and 2 ,carboxyl groups,that is ll8 ]carbon atoms per carboxyl and there is usually present'acertain amount of ,trimer acid containing 54 carbon atoms which, inturn, has 3 carboxyl groups; again 18 carbon atoms per carboxyl group.'Esters of acids having less than about 6 carbon atoms per carboXylgroup are relatively less efifective than esters of highermolecularweight acids but they are useful under very mild conditions, even theacetate showing at least the beginning of rust inhibition. However forheavy commercial service, it is usually desirable that the esterifyingacid contain 6 or more carbon atoms per carboxyl. No upper limit for thecarbon atom number per carboxyl group has as yet been found but itcertainly lies well above 30, probably 60, and may well include all ofthe higher, stable organic acids. 7

The following examples are offered as showing the characteristics andpreferred method of use of the invention but are not intended to limitthe scope of the claims in any Way. 7

EXAMPLE 1 A rust test was carried out as follows: Various solutions ofinhibitors were prepared either in a petroleum hydrocarbon (B.P.90-100IC.) or in a crankcase type petroleum hydrocarbon lubricant (540cps. at 25 0., initial boiling point 375 C.). A mild steel bar wasturned in a lathe and the chips, as formed, were allowed to fall intothe solutions; The solutions were then drained away from the chips,shallow Petri dishes and subjected to the corrosive en vironment of ahumidity chamber which was maintained at about 55 C. and the relativehumidity was cycled through 100% periodically, about every two hours.The chips were inspected frequently, usually daily, and the time wascounted until 10% of the chips had visible signs of rust. In thefollowing table are recorded these times for various solutions.

which were then placed in acids. I In the case of dimer acid, thestructure has not yet been completely elucidated. It is known that someof the molecules may contain unsaturation. Dimer acid is well known, itspreparation is described in I. Am. Soc.

Oil Chemists 24, 65 (March 1947) and it is referred to often as in US.Patent 2,464,399, It is essentially polymerized linoleic acid having,typically, an average molecular weightof about 600, an acid value of 180mg. KOI-I per gram, dimer content 75%, trimer content 25%, monomercontent of 3%, sp, gr. 15 C.=0.95. This type compound is available inseveral slight modifications.

In addition, the preferred esters of the C alcohols have the superiorityover esters of other polyhydroxy alcohols such as glycerol, sorbitol,pentaerythritol in that there is complete solubility without additives,and chemical stability, and the inhibition is outstanding, nosynergists, tars, residues and the like being necessary.

EXAMPLE 2 As further evidence of excellence, 0.5% and 2% solutions ofinhibitors were prepared in the high boiling hydrocarbon of Examplel andsubjected to thestatic drop test of Baker, Jones and Zisman (Ind. Eng.Chem.

41, 137 (1949) for 2 days at C. with the following results.

butanediol dioleate butanetrlol butanediol monooleate monooleateglyceryl monooleate (Prior Art) butanediol diester' of a dimer acidpasses..-" fails. Do.

fails fails passes"..-

passes do. do

Duration of 1 0% rusty chips Glyoeryl oleate (Prior Art) weeksButanediol Butanetriol monooleate, monooleate,

days

Butanediol Dilaurate, days Butanediol distearate, days Butanedioldioleate,

days

Percentage inhibitor in low boiling hydr8ca5rbon (SO-100 0.):

Percriiiflirihiff hi li'iciun lii droearbon (375 0.):

In the above table the symbols more than indicate that the test wasdiscontinued before the required rust developed. All of the abovesystems were in solution at room temperature. The glyceryl oleate was,however, dark colored and gummy on the chips, especially in the higherconcentrations. Possibly this is due, in part, to hydrolysis, followedby oxidation or polymerization.

The table indicates a large factor of superiority of esters ofbutanediol and butanetriol over glyceryl oleate. Various otherglycerides such as the stearates, palmitates, and mixtures were found tobe inferior, as were their intermediates (e.g. glycerol, oleic acid,stearic acid). The table also shows that short chain acid esters are notas efiicient inhibitors as the' longer chains; in addition to the.dilaurate shown in the table, the dibutyrate, diacetate and the likeexhibited less inhibition under the severe conditions of the test. l

The table indicates the superiority of the esters of many unsaturatedacids over corresponding saturated monoesters being trations; 7 I

In addition, the preferred inhibitors and related compounds areconvenient to use, being liquids at usual temperatures.- For example,the monooleate of butanetriol is a mobile liquid at room temperature,becoming somewhat viscous but easily manipulated at 5 C. and when frozencompletely melts at 0 C.

Examples of other esters whichmay be employed for the inhibition of rustin various environments are butanetriol dioleate, butanetriol trioleate,'butanetriol monoester, diester and triester of dimer acid, as well asthe ricinoleates, the linoleates, the linolenates, palmitates, and thelike of both polyhydric alcohols.

These compounds may be dissolved in various liquids such as petroleumhydrocarbons, gasolines, kerosenes, diesel fuels, motor oils, crankcaseoils, greases, pet-rolatums and the like, alcohols, fats, solvents suchas dry cleaning solvents, degreasing solvents, paints, coatings,synthetic. liquids, such as lubricants and greases, hydraulic moreeffective, and at lower concenfluids and the like, and when socompounded impart protection to the ferrous metals contacted by thesefluids from the deleterious elfects of rust, the choice of ester beinggoverned by such factors as the severity of the corrosive environment,the specific liquid to be inhibited and so forth.

The inhibitors, in addition to protecting containers such as tanks,pipelines, machinery, processing equipment, conduits, may also be usedin the manner of slushing compounds when a metal to be protected isdipped into a solution of the inhibitor, or the solution is applied as afilm, using such implements as spraying apparatus, paint brushes, rags,or the like.

Various other uses will suggest themselves. The agents may be introducedinto oil wells for the prevention of rust to the metal parts, andcertain of them may be of use in the acidization process.

These inhibitors are easily removed when their services are no longerrequired. They deposit no residue when ignited which adds to theirutility in that, for example, when used in crankcase oils, there is nofouling of spark plugs, piston rings, no preignition-causing residuesare deposited.

Thus the compositions of matter of the present invention provide new anduseful rust inhibitors in the form of an ester of butane polyalcoholswith acids, preferably organic of substantial molecular weight asindicated, such as from 12 to 20 or 25 or more carbon atoms per carboxylgroup.

While there are above disclosed but a limited number of embodiments ofthe compositions of matter of the present invention, it is possible toprovide still other embodiments without departing from the inventiveconcept herein disclosed, and it is therefore desired that only suchlimitations be imposed upon the appended claims as are stated therein orrequired by the prior art.

The invention claimed is:

l. A corrosion inhibited petroleum hydrocarbon composition consistingesentially of a major amount of a petroleum hydrocarbon and a minoreffective corrosion inhibiting amount of a compound selected from thegroup consisting of oleic acid esters of 1,4-butanediol and 1,2,4-butanetriol and dimerized linoleic acid esters of 1,4-butanediol and1,2,4-butanetriol.

2. A corrosion inhibited petroleum hydrocarbon composition consistingessentially of a major amount of a petroleum hydrocarbon and a minoreffective corrosion inhibiting amount of 1,4-butanediol monooleate.

3. A corrosion inhibited petroleum hydrocarbon composition consistingessentially of a major amount of a petroleum hydrocarbon and a minoreffective corrosion inhibiting amount of 1,2,4-butanetriol monooleate.

4. A corrosion inhibited petroleum hydrocarbon composition consistingessentially of a major amount of a petroleum hydrocarbon and a minoreffective corrosion inhibiting amount of 1,4-butanediol dioleate.

5. A corrosion inhibited petroleum hydrocarbon composition consistingessentially of a major amount of a petroleum hydrocarbon and a minoreffective corrosion inhibiting amount of the diester of dimerizedlinoleic acid and 1,4-butanediol.

References Cited in the file of this patent UNITED STATES PATENTS2,201,484 Farrington et al May 21, 1940 2,368,602 Weiss Jan. 30, 19452,434,490 Duncan Jan. 13, 1948 2,482,517 Schiermeier et al Sept. 20,1949 2,527,889 Moore Oct. 31, 1950 2,531,801 Blake Nov. 28, 19502,558,025 Wicks June 26, 1951 2,655,522 Malkemus Oct. 13, 1953 2,763,612Raifsnider et al. Sept. 18, 1956

1. A CORROSION INHIBITED PETROLEUM HYDROCARBON COMPOSITION CONSISTINGESENTIALLY OF A MAJOR AMOUNT OF A PETROLEUM HYDROCARBON AND A MINOREFFECTIVE CORROSION INHIBITING AMOUNT OF A COMPOUND SELECTED FROM THEGROUP CONSISTING OF OLEIC ACID ESTERS OF 1,4-BUTANNEDIOL AND1,2,4BUTANETRIOL AND DIMERIZED LINOLEIC ACID ESTERS OF 1,4-BUTANEDIOLAND 1,2,4-BUTANETRIOL.